1. Field of the Invention
The invention is in the field of production of niobium alloys, particularly titanium niobium alloys.
2. Description of the Prior Art
The alloying of other metals with niobium (formerly called columbium) is a well developed art and includes processes for alloying titanium with niobium in the production of electrical superconductors. Examples of the latter technology are found in U.S. Pat. Nos. 3,167,692 and 3,268,373.
Processes have been proposed for reducing niobium oxides by mixing such an oxide with a metallic reducing agent, see U.S. Pat. Nos. 2,789,896 and 4,419,127.
The use of aluminum in such processes for creating a thermite reaction to supply the necessary heat is common practice, see U.S. Pat. Nos. 3,372,022; 4,164,417; 4,169,722; and 4,504,310, and Japanese Patent No. 47-22313.
The current, commercially accepted practice of producing titanium niobium alloys, particularly as superconductors, is to reduce niobium pentoxide (Nb.sub.2 O.sub.5) with excess aluminum and a fluxing agent, such as barium oxide, in a thermite reaction to yield niobium metal and an Al.sub.2 O.sub.3 /BaO slag. The niobium metal is separated from the slag and purified by electron beam melting and is then powdered (which is done by the relatively expensive process of hydriding the metal, crushing the hydride, and then dehydriding the powder) and mixed with titanium powder (powdering of alloy constituents, although difficult, has been necessary to minimize phase segregation and achieve sufficient homogenity). The mixture is arc melted to provide the desired alloy and is cast into ingots of the alloy.